I've been piecing together the life story of an ancestor. I've been relatively lucky. I have a lot of written sources for this family - from memoirs, to local newspapers, to family association records - but I'm also missing a lot. Why?
There were two main reasons. My ancestors were busy people. Working the farm, attending to your family, and attending to the town didn't leave much time. They didn't write much down until they were elderly (the youngest was in their early 80s). And they wrote what they assumed their children didn't know. I've got great descriptions of my ancestors' childhoods. But things get much thinner when I need information about their adult lives.
They assumed their children would tell those stories. Unfortunately, they assumed wrong. Some of their children wrote, but like many children, they saw themselves at the center of their own childhood. How often did you know about your parents' relationship or where they met? Others were just too busy. In those families, the tradition fell away.
So, to my plea... Don't leave those gaps in your children's genealogy. Write a letter to a child or grandchild. It doesn't have to be long. Just give the basic details about your life, about what you remember. Yes, they'll still miss a lot - but at least they'll have something. And if they don't care now, put in the safety deposit. Maybe you'll save them a few "I wish I'd asked."